The present disclosure relates to a process for enhancing procatalyst properties (selectivity) and/or formant polymer properties (bulk density). The present disclosure also relates to the improved procatalyst compositions and the improved formant polymers produced by these processes.
Worldwide demand for olefin-based polymers continues to grow as applications for these polymers become more diverse and more sophisticated. Known are Ziegler-Natta catalyst compositions for the production of olefin-based polymers. Ziegler-Natta catalyst compositions typically include a procatalyst containing a transition metal halide (i.e., titanium, chromium, vanadium), a cocatalyst such as an organoaluminum compound, and optionally an external electron donor. Ziegler-Natta catalyzed olefin-based polymers typically exhibit a narrow range of molecular weight distribution. Given the perennial emergence of new applications for olefin-based polymers, the art recognizes the need for olefin-based polymers with improved and varied properties.
Known are catalyst compositions containing a substituted phenylene aromatic diester as an internal electron donor used for the production of olefin-based polymers. Desirable would be Ziegler-Natta procatalyst compositions containing a substituted phenylene aromatic diester for the production of olefin-based polymers that provide high selectivity during polymerization. Further desired is a procatalyst composition that increases the bulk density of the formant polymer.